In a manner known per se, certain rigid-shell ski boots comprise a shell bottom under a boot upper consisting of a rear piece (or rear cover) and a front piece (or oversleeve) covering a longitudinal slit in the upper area of the shell base. Rearward traction, exerted when the top is closed over the skier's leg, draws the edges of the slit together over the skier's instep so as to hold the foot in the boot by deformation of the upper portion of the shell base. Such boots are described in German Patents Nos. DE 32 47 516 and DE 35 06 056.
Other types of boots also make use of foot-retention means contained within the shell base that act independently of any deformation in said shell base. Such examples are disclosed in French Patents Nos. 2,343,437 and 2,345,097. German Patent Application No. DE 34 29 237 describes another principle for gripping the foot through deformation of the shell base induced by traction exerted on cables passing over the flexible edges of the slit in the shell base by means of a tensioning system installed on the piece covering the front portion of the boot.
Finally, French Patent No. 2,556,187 describes a type of boot construction in which the tightening principle disclosed in French Patent No. 2,345,047 is applied to flexible sections anchored in the shell base itself and extending within a rigid, non-deformable structure of the front portion of the boot, covering the entire area of the boot from the tip to the instep.
The use and application of the boots described in German Patents Nos. DE 35 06 056 and DE 32 47 516 show that with this type of boot a base is required in order to ensure a leakproof boot, and that the edges of the slit must be made flexible enough to hold the foot effectively. It appears that these requirements are difficult to meet, since the top cover of such boots, which contributes to controlling the bendings of the leg of the skier, produces a relatively continuous movement of the cover with respect to the shell base in the course of skiing. This movement of the cover has as its consequence the alteration of the conditions under which the foot was initially retained.
Other boots, such as those disclosed in Swiss Patent No. 506,960, include a rigid shell provided with an opening and closing device through which the foot passes, while the foot is held by means of a fabric gaiter made integral with the insole and fastened to elastic retaining means that make use of cords and laces. In such shoes, all parts of the foot are subjected to the pressure of the retaining means; this is relatively awkward or even painful for certain parts of the foot such as the metatarsal-phallangian articulations, which undergo considerable changes in position across their width, especially when the skier changes position, changes which alter the distribution of weight on the foot.
Also known are safety boots in which the flexible upper is provided with conventional lacing means, such as those described in U.S. Pat. No. 3,798,804, and which comprise a rigid upper safety cover that pivots freely about an axis situated in the toe area. In this example, the boot is constructed with a number of transverse tongues fastened to the lacing means and interconnected by means of a flexible material so as not to interfere with the bending of the upper in walking. Such boots are able to hold feet well enough for walking, but the structure of the freely pivoting cover makes it impossible to ensure a leakproof ski boot that will absorb the forces exerted on the rigid shell base by the top of the boot.
SUMMARY OF THE INVENTION
The invention offers a ski boot having a foot-gripping capacity comparable to that provided by conventional, lace-up walking shoes while retaining the qualities of control and stress-absorption of rigid-shell ski boots. To this end, the invention joins internal foot retention means to the shell base, respecting the shape of the skier's foot without exerting stress or pressure on the bony areas of the joints of the forefoot and heel in particular, allowing said bony areas to change position Within the shell base. When the foot is subjected to the various stresses involved in the act of skiing.
The ski boot according to the invention comprises a rigid shell base below a boot upper equipped with an opening and closing system through which the skier's foot passes, said shell base at least partially enclosing the foot from its forward end back approximately to the area corresponding to the instep. The boot is characterized by the fact that at least one transverse tongue is made . and at least partially encircles the top of the skier's foot. The tongue can be drawn down with respect to the shell base along a drop line that is longitudinal to the boot, elevated with respect to the plane of the sole, and located in a plane that passes approximately over the heads of the metatarsal and malleolian bones of the foot. Along the length of the boot, the tongue is delimited by two secant planes intersecting the plane of the sole and passing through the heads of the malleolian and metatarsal bones, respectively.
Advantageously, the transverse tongue is flexible with respect to the wall of the shell base to Which it is joined. An internal foot-retention device, of a type known per se, is arranged so as to draw the tongue down against the top of the skier's foot without deforming the shell base or any other of the parts of the rigid shell (when the latter consists of several assembled parts).
Thus, according to a preferred embodiment of the invention, the foot-retention means, consisting of the tongue, are flexible with respect to the corresponding surface of the shell base beyond a delimiting line below which the shell base houses the bony parts of the calcaneum and the metatarsal heads of the skier's foot. It is understood that if the boot is built by joining the tongue to the wall of the shell base, the drop line of the transverse tongue may or may not be coextensive with the line along which it is attached to the shell base. It should also be noted that the entire area of the shell base (or of its structural equivalent) lying below the drop line of the transverse tongue is essentially rigid, so that the areas containing the heads of the foot bones are housed in a non-deformable casing within which a custom-fitted lining may be provided to envelop the foot comfortably. The transverse tongue is designed to grip the foot by enveloping its upper surface in a flexible manner.
The invention is not limited to the use of a single interior transverse tongue, but extends to all constructions using a series of tongues arranged on one or both sides of he boot. In such cases, the drop line of each tongue would be coextensive with the general drop line on each side of the boot.
The invention admits of many variants of the foot-retention means, or tongues. For example, the tongues may be made of a relatively flexible, supple, and/or expandable material. Depending on design requirements, these tongues may be joined by various assembly mean to the non-deformable walls of the shell base or may constitute an extension of said walls. Finally, the tongues may also include bend zones in the form of articulations and/or arrangements such as grooves, channels, and the like, capable of permitting bending from a certain line by altering the resistance of the materials used in those areas. To ensure optimal distribution of the gripping or holding pressures exerted by the tongues on the skier's foot, the tongues possess a certain degree of flexibility and/or special shapes or forms such as a plurality of notches or deformable sections capable of adapting to the shape of the foot.
The rigid portions of the shell of the boot may be constructed in different ways, depending among other things on the manner in which the boots are to be put on. Thus the shell base may be made of a single enveloping piece below a boot top comprising an oversleeve and a rear cover, with the latter being rearwardly pivotable in order to allow the skier to insert his or her foot. For a front-opening construction, the shell base may be provided with an upper cover, removable from, or articulated on, the shell base.
Regardless of the method of constructing or assembling the rigid sections of the boot shell, the foot-retention means (consisting of the transverse tongues) are arranged under said rigid sections within the delimited area and space set forth above, and at least one tightening and/or adjusting device is to bring said retaining means together, particularly by drawing their free ends together so as to apply them to the top of the foot.
It is obvious that a comfort lining could be placed between the tongues and the foot if desired.